This invention relates to a vehicle headlight comprising a reflector, a light source positioned at a focal area of the reflector, a lens positioned in front of the reflector, a sheetmetal screen placed between the reflector and the lens whose edge creates a light-dark border of a light pattern, and a frame that supports the lens and the screen.
European patent document (EP 0 200 928 A2) discloses a vehicle headlight of this type. A light unit of this headlight comprises an ellipsoidal reflector, a light source positioned inside the reflector, and a frame, placed in front of the reflector and attached to an outer circumferential edge of the reflector, which supports a lens and a screen placed between the lens and the reflector. An incandescent or gas discharge lamp may be used as the light source. The frame is manufactured from deep-drawn sheet steel. Deep-drawn sheet steel can be plastically shaped quite readily, and therefore exhibits very little elasticity. The frame has a support ring, formed during the deep drawing process, into which the lens and a snap ring that fastens the lens in the support ring are inserted from a front of the light unit. Support legs that are fastened on the outer edge of the reflector are formed as a single unit with the support ring. The screen is formed as a single unit with the support ring via an arm-like mounting element that is positioned between two support legs of the frame. The screen is pivoted toward the lens about a pivot formed at a bending area of the arm-like mounting element. The screen is plate-shaped and extends in a plane that is transverse to a direction in which light exits. An edge of the screen extending in the plane is located at a focal area of the lens and creates a light-dark border of a light pattern of the light system.
One section of a screen-edge portion extends horizontally, while another section runs diagonally down from the optical axis. In this way, an asymmetrical light distribution occurs on a roadway. The screen extending in a plane has free end sections at its lateral free ends bent toward the lens, which can be attached to the respective adjacent support legs by laser welding. The screen can also be attached to the support legs via soldering, rivets, or screws. An automatic engaging, or snapping, of the screen to the support legs is impossible owing to insufficient elasticity of deep-drawn sheet steel. In order to maintain a sufficiently long spring excursion at locking locations, the end sections of the screen, that are to be locked onto the support legs, would have to be very long. However, a spring force would be very small and therefore a secure locking of the screen to the frame would not be assured.
In a vehicle headlight disclosed in European patent document (EP 0 212 211 B1), a light system serves to provide fog light. Such light systems are much smaller than light system that generate asymmetrical light, and, because of their small construction, they comprise at most one screen that has a bowed or curved, screen-edge portion. The bowed screen-edge portion is formed by a screen that is a cylindrical wall section. The lens and the screen are inserted, from a reflector side, into a a frame connected to the reflector, and fastened to a support ring of the frame. In a headlight known in the art, the bowed screen is manufactured by zinc die casting, and has riveting pins formed on it with which the screen can be affixed to the frame. Such screens are expensive to manufacture, and installing them is complicated and time-consuming.
An object of this invention is to provide a vehicle headlight of a type including a reflector, a light source positioned at a focal area of the reflector, a lens positioned in front of the reflector, a sheet-metal screen placed between the reflector and the lens an edge of which creates a light-dark border of a light pattern, and a frame that supports the lens and the screen, structured so that the screen can be fastened to the frame automatically and with considerable retention force without requiring the use of an additional fastening elements.